BACKGROUND: Evidence from observational studies suggests that inadequate folate status enhances colorectal carcinogenesis, but results from some randomized trials do not support this hypothesis. OBJECTIVE: To assess the effect of folic acid supplementation on recurrent colorectal adenoma, we conducted a cost-efficient, double-blind, randomized trial among participants of 2 large prospective cohorts, the Health Professionals Follow-Up Study and the Nurses' Health Study. DESIGN: Participants were randomly assigned to receive folic acid (1 mg/d) (n = 338) or placebo (n = 334) for 3-6.5 y. The primary endpoint was any new diagnosis of adenoma during the study period (May 1996-March 2004). Secondary outcomes were adenoma by site and stage and number of recurrent adenomas. Associations were also examined by plasma folate concentrations at baseline. RESULTS: Incidence of at least one recurrent adenoma was not significantly associated with folic acid supplementation [relative risk (RR): 0.82; 95% CI: 0.59,1.13; P = 0.22]. Among participants with low plasma folate concentrations at baseline (<or=7.5 ng/mL), those randomly assigned to receive folic acid experienced a significant decrease in adenoma recurrence (RR: 0.61; 95% CI: 0.42, 0.90; P = 0.01), whereas for subjects with high folate concentrations at baseline (>7.5 ng/mL), supplemental folic acid had no significant effect (RR: 1.28; 95% CI: 0.82, 1.99; P = 0.27, P(interaction) = 0.01). Contrary to findings from another clinical trial, there was no evidence for an increased risk of advanced or multiple adenomas. CONCLUSIONS: Our results do not support an overall protective effect of folic acid supplementation on adenoma recurrence. Folic acid supplementation may be beneficial among those with lower folate concentrations at baseline. This trial was registered at clinical trials.gov as NCT00512850.
RCT Entities:
BACKGROUND: Evidence from observational studies suggests that inadequate folate status enhances colorectal carcinogenesis, but results from some randomized trials do not support this hypothesis. OBJECTIVE: To assess the effect of folic acid supplementation on recurrent colorectal adenoma, we conducted a cost-efficient, double-blind, randomized trial among participants of 2 large prospective cohorts, the Health Professionals Follow-Up Study and the Nurses' Health Study. DESIGN:Participants were randomly assigned to receive folic acid (1 mg/d) (n = 338) or placebo (n = 334) for 3-6.5 y. The primary endpoint was any new diagnosis of adenoma during the study period (May 1996-March 2004). Secondary outcomes were adenoma by site and stage and number of recurrent adenomas. Associations were also examined by plasma folate concentrations at baseline. RESULTS: Incidence of at least one recurrent adenoma was not significantly associated with folic acid supplementation [relative risk (RR): 0.82; 95% CI: 0.59,1.13; P = 0.22]. Among participants with low plasma folate concentrations at baseline (<or=7.5 ng/mL), those randomly assigned to receive folic acid experienced a significant decrease in adenoma recurrence (RR: 0.61; 95% CI: 0.42, 0.90; P = 0.01), whereas for subjects with high folate concentrations at baseline (>7.5 ng/mL), supplemental folic acid had no significant effect (RR: 1.28; 95% CI: 0.82, 1.99; P = 0.27, P(interaction) = 0.01). Contrary to findings from another clinical trial, there was no evidence for an increased risk of advanced or multiple adenomas. CONCLUSIONS: Our results do not support an overall protective effect of folic acid supplementation on adenoma recurrence. Folic acid supplementation may be beneficial among those with lower folate concentrations at baseline. This trial was registered at clinical trials.gov as NCT00512850.
Authors: E B Rimm; E L Giovannucci; W C Willett; G A Colditz; A Ascherio; B Rosner; M J Stampfer Journal: Lancet Date: 1991-08-24 Impact factor: 79.321
Authors: E Giovannucci; M J Stampfer; G A Colditz; E B Rimm; D Trichopoulos; B A Rosner; F E Speizer; W C Willett Journal: J Natl Cancer Inst Date: 1993-06-02 Impact factor: 13.506
Authors: Richard Jaszewski; Sabeena Misra; Martin Tobi; Nadeem Ullah; Jo Ann Naumoff; Omer Kucuk; Edi Levi; Bradley N Axelrod; Bhaumik B Patel; Adhip P N Majumdar Journal: World J Gastroenterol Date: 2008-07-28 Impact factor: 5.742
Authors: E Giovannucci; M J Stampfer; G A Colditz; D J Hunter; C Fuchs; B A Rosner; F E Speizer; W C Willett Journal: Ann Intern Med Date: 1998-10-01 Impact factor: 25.391
Authors: Jung Eun Lee; Walter C Willett; Charles S Fuchs; Stephanie A Smith-Warner; Kana Wu; Jing Ma; Edward Giovannucci Journal: Am J Clin Nutr Date: 2011-01-26 Impact factor: 7.045
Authors: Tim Y Hou; Laurie A Davidson; Eunjoo Kim; Yang-Yi Fan; Natividad R Fuentes; Karen Triff; Robert S Chapkin Journal: Annu Rev Nutr Date: 2016-07-17 Impact factor: 11.848
Authors: Todd M Gibson; Stephanie J Weinstein; Ruth M Pfeiffer; Albert R Hollenbeck; Amy F Subar; Arthur Schatzkin; Susan T Mayne; Rachael Stolzenberg-Solomon Journal: Am J Clin Nutr Date: 2011-08-03 Impact factor: 7.045
Authors: Jung Eun Lee; Esther K Wei; Charles S Fuchs; David J Hunter; I-Min Lee; Jacob Selhub; Meir J Stampfer; Walter C Willett; Jing Ma; Edward Giovannucci Journal: Cancer Causes Control Date: 2012-02-26 Impact factor: 2.506
Authors: Yiqing Song; Joann E Manson; I-Min Lee; Nancy R Cook; Ligi Paul; Jacob Selhub; Edward Giovannucci; Shumin M Zhang Journal: J Natl Cancer Inst Date: 2012-10-12 Impact factor: 13.506